Warrior or DK (or Warlock)?

I've never played the above classes to max level before and am considering one. I'm mostly a PvP player, although pve viability is also nice to have.
I enjoy BG's very much, and I've never played a flag carrier role. So i'm interested in rolling a class that is capable of doing that if i want to try something new.

So, between warriors and DK's (with 5.1 patch coming in mind), which class would you rather roll? Or I am also interested in leveling my warlock to 90. I've never seriously played a lock before but with many changes they got in MoP, they do seem pretty interesting also.
At the moment, I'm most interested in warrior, but the tricks that locks and DK's also seem quite fun to play with.

I'm guessing warriors won't be cooldown-stacking one shot hero every 5 minutes come 5.1 (or will they? xD) but i think their mobile melee playstyle is still fun (as opposed to a rogue that i have... let's not go there).
I've seen a lot of warrior lately, but..
How are DK's? And warlocks? They are some of the least played classes out there (we all know DKs had their days).

As far as a DK is concerned, what's a fun spec to play with? I know frost brings a lot of damage, but what are their weaknesses? Also, how's Unholy now (and in 5.1).

Lastly, i'm wondering what's a fun spec for warlocks that's viable. I'm not too interested in destro one-shot wonder, but I do find Demonology interesting (and possible flag carrying in random BG's). The idea of caster flag carrying is pretty fun to play around in PUG's.

DKs aren't getting a lot of changes. They are not nearly as mobile as warriors are in the sense that they are not darting from place to place all over the arena. However, on my UHDK, I can have up to 5 trinkets for various forms of CC. The trick is knowing which goes with which. So I never lose control of my character or get slowed, but I'm only able to move around at normal speed, where a warrior can hop about like a rabbit on crack. UH is quite fun, especially in BGs, spreading (potentially very powerful) dots around then controlling classes while you stack necrotics. It's a very fast-paced play, especially with Blood Tap thrown in now and again between 1-second GCDs. That said, warriors can go very defensive, while I feel somewhat squishy on my DK. I can tank a good amount of damage very quickly, or a little extra over time, but I cannot stand toe to toe with a warrior with all his CDs blown (though no class can, really) unless I'm expecting it. UH is not very bursty, but can put out surprising pressure in a pinch.

All of the warlock specs play completely differently from one another. It's really more like having three classes and switching between them. Demo is very bursty and has incredible AoE with Auras, Hellfire, Hand of Gul'dan (especially glyphed combined with Mannoroth's Fury), etc. But you have to build that burst, so until you turn into a demon and absolutely wreck something, you feel a little weak. However, locks can seriously tank damage now, and they do work as FCs *some of the time* (really dependent on healers and how much they like you). It's quite nice. But the play is not nearly as fast-paced as my DK.

Do you like ranged casters? Because that's what you'll be as a warlock no matter how you play it. Unless you're a demon, you still have a standard GCD. As a DK everything is fast, but I still feel like something of a caster as I can make myself known at range, or when disarmed. I play them both as counterpoints to one another. What one lacks, the other has. They both have spells, though, and are not super mobile a la warriors. But I have fun.

We can't determine what class you should play, what class you enjoy is upto you and just because we enjoy one of the classes doesn't mean you will.

This is true, however we CAN help him arrive at a conclusion so why not post constructively?

OT: If you want an all-round good class that can adapt to any given situation I'd say a Warlock, great in BGs as destro, king of 3vs3 in terms of a dps class (imo atleast), and just in general it's a FUN to play class from my experience.

I would have to say playing a warrior for 2 and a half expansions I don't think there's any other class i could enjoy as much. All three options are very viable right now but even when warriors were pretty weak in cata i wouldn't have traded mine for anything else.

For PvP I'd pick warrior if you fancy melee or warlock if you're cool with the caster thing. DK however is absolutely the most fun PvE class in game atm if you like doing dmg or tanking, imo. DK survivability/mobility isn't that great (atleast compared to warriors) in PvP right now although frost can do some serious damage, even outside 5 minute cooldowns. If you play arena, DK has only a handful of decent/viable comps, the usual PHD & TSG whereas warriors and warlocks both have much more options.

I've never played the above classes to max level before and am considering one. I'm mostly a PvP player, although pve viability is also nice to have.
I enjoy BG's very much, and I've never played a flag carrier role. So i'm interested in rolling a class that is capable of doing that if i want to try something new.

So, between warriors and DK's (with 5.1 patch coming in mind), which class would you rather roll? Or I am also interested in leveling my warlock to 90. I've never seriously played a lock before but with many changes they got in MoP, they do seem pretty interesting also.
At the moment, I'm most interested in warrior, but the tricks that locks and DK's also seem quite fun to play with.

I'm guessing warriors won't be cooldown-stacking one shot hero every 5 minutes come 5.1 (or will they? xD) but i think their mobile melee playstyle is still fun (as opposed to a rogue that i have... let's not go there).
I've seen a lot of warrior lately, but..
How are DK's? And warlocks? They are some of the least played classes out there (we all know DKs had their days).

As far as a DK is concerned, what's a fun spec to play with? I know frost brings a lot of damage, but what are their weaknesses? Also, how's Unholy now (and in 5.1).

Lastly, i'm wondering what's a fun spec for warlocks that's viable. I'm not too interested in destro one-shot wonder, but I do find Demonology interesting (and possible flag carrying in random BG's). The idea of caster flag carrying is pretty fun to play around in PUG's.

1. Only you can decide whats more fun for you, its only burst/dmg go with the warrior, he far outclasses dks and locks. Even though locks still have high critting chaos bolt i do not think destro is vaible in arenas.

2. look at the setups viable. Warr far has more working in this saison than dk/lock.

3. wouldn't compare bursty class like warr and to an extend frost dk(non plate only), to a class that can spam a ranged CC, (fear warlock) If you ever did arenas you know the huge difference and won't ask such questions here.